In this Feb. 24, 2016, file photo, Republican members of the Senate Armed Services Committee, Sen. Lindsey Graham, R-S.C., center, and committee chairman John McCain, R-Ariz., speak at a news conference on Capitol Hill in Washington. Graham and McCain are assembling a harsh critique of Donald Trumps worldview by soliciting rebuttals from U.S. military leaders that challenge the accuracy and legality of his most provocative foreign policy positions. (AP Photo/J. Scott Applewhite, File)

WASHINGTON (AP) — The Senate’s leading Republican voices on national security are assembling an indictment of Donald Trump’s worldview by soliciting rebuttals from U.S. military leaders that challenge the accuracy and legality of the GOP presidential front-runner’s most provocative foreign policy positions.

Over the past few months, Sens. John McCain of Arizona and Lindsey Graham of South Carolina, two of Trump’s sharpest GOP critics, have used their posts on the Senate Armed Services Committee to fact-check Trump’s claims.

Without mentioning the bombastic billionaire’s name, they’ve asked senior officers who testify before the committee about waterboarding extremists, the consequences of targeting terrorists’ families, and whether NATO and America’s other key alliances have become obsolete.

Connecting the threads over weeks of hearings would produce a record of remarks that could be strung together and used by opponents of the presidential candidate.

To demonstrate his fitness to be commander in chief, Trump is planning to tone down his brash personality and deliver a foreign affairs address on Wednesday — the first in a series of policy speeches. He also is planning a separate speech on the military, telling The Associated Press in a recent interview that people may be surprised by “how well I’ll handle matters relative to the military.”

Omitting Trump’s name from the conversation allows the generals and admirals questioned by the senators to stay apolitical and out of the 2016 presidential campaign. But it’s obvious that McCain, the committee’s chairman, and Graham, who waged an unsuccessful bid for his party’s White House nomination, are asking about positions Trump has staked out that have rattled the Republican Party and unnerved U.S. allies.

Aides to the senators said there’s no coordination or strategy between the two. But McCain and Graham are close friends and foreign policy hawks. It’s not unusual to see them together on the floor of the Senate, hammering the Obama administration over the Iran nuclear deal, the civil war in Syria or troop levels in Afghanistan.

Graham also wrote the chairman of the Joint Chiefs of Staff, Marine Corps Gen. Joseph Dunford. Without citing Trump’s name, he inquired about the billionaire’s pledge, if elected, to bring back the use of waterboarding — which causes the sensation of drowning — and worse against captured militants. Congress has outlawed waterboarding along with other so-called enhanced interrogation techniques.

Trump also said he would order the military to kill family members of militants who threaten the U.S., a position he has since retreated from after being heavily criticized.

Dunford responded to Graham last week in a carefully worded letter that said violating the laws of war “diminish the support of the American people and the populace of Democratic states, including allies who might otherwise support or participate in coalition operations.”

Graham, a retired Air Force lawyer, has called Trump’s foreign policy “gibberish” and “ill-conceived.” Graham half-heartedly endorsed Sen. Ted Cruz of Texas for president because Cruz is “not completely crazy.”

McCain, an ex-Navy fighter pilot and the 2008 GOP presidential nominee, hasn’t wavered from his position that he will support the Republican nominee. But he’s bristled over what he’s called Trump’s “uninformed and dangerous statements on national security issues.”

Examples of McCain’s and Graham’s fact-checking approach were on display this past week.

On April 19, when the Army general selected to lead U.S. forces in South Korea testified before the committee, McCain seized the opportunity to undermine Trump’s suggestion that the U.S. withdraw its forces from the South because Seoul isn’t paying enough to cover the cost of the American military presence.

“Isn’t it the fact that it costs us less to have troops stationed in Korea than in the United States, given the contribution the Republic of Korea makes?” McCain asked Gen. Vincent Brooks.

Yes, Brooks said, telling McCain the South Koreans pay half, or $808 million annually, of the U.S. presence there.

Brooks added that the South Koreans are footing the bill for more than 90 percent of a $10.8 billion project to build a base where U.S. troops will be stationed.

Two days later, Trump’s claim that NATO is irrelevant and ill-suited to fight terrorism came under the microscope. As president, Trump has said he would force member nations to increase their contributions, even if that risked breaking up the 28-country alliance.

Responding to a series of questions from Graham, Army Gen. Curtis Scaparrotti, picked to be the top American commander in Europe, assured the committee of NATO’s critical importance to the U.S. Breaking up the alliance, Scaparrotti warned, would benefit Russia, the Islamic State group and even the Taliban in Afghanistan.

The issue of torture is personal to McCain, who was a prisoner of war in North Vietnam for more than five years and badly abused by his captors. During a committee hearing in February, McCain asked Director of National Intelligence James Clapper if he agreed that information gained through waterboarding and other methods of torture came at too high a cost for the United States.

“I do,” said Clapper, a retired Air Force lieutenant general.

“Isn’t it the fact that this is —- American values are such that just no matter what the enemy does, that we maintain a higher standard of behavior? And when we violate that, as we did with Abu Ghraib, that the consequences are severe?” said McCain, referring to the prison scandal in Iraq.

“Yes, sir,” Clapper responded.

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